Does radiator foil work? Low-cost insulation hacks that actually make a difference
Is it possible to insulate your home on the cheap with radiator foil hacks and other cost-effective tricks? If you can’t afford major works or you’re looking to top up existing insulation, then this guide is for you.
Discover five proven low-cost hacks that can make your home more comfortable and cheaper to live in, plus find out which hacks to avoid and how to insulate your rented home without breaching your tenancy agreement.
Radiator foil
What is radiator foil and how does it work?
Radiator foil is placed between your radiator and the wall with the aim of deflecting heat back into the room instead of being absorbed into the wall. This means more of the radiator’s heat is used to warm the room, bringing it up to temperature more quickly and reducing the amount of energy required to heat your home.
Does radiator foil really make a difference?
Radiator foil can make a difference, but it depends on when and where it’s used. It’s most effective when fitted behind radiators fixed to external, uninsulated solid walls in older homes that suffer from a lack of good insulation like cavity wall insulation and modern double-glazed windows.
Studies show that when dedicated radiator foil or pre-cut radiator panels are fitted to uninsulated external walls correctly, they can trim up to £25 a year off your heating bills, according to the Energy Saving Trust.
How to fit radiator foil effectively
You can purchase radiator foil in rolls – typically 5-10 metres long by 50-60 cm wide – or buy pre-cut panels. Radiator foil costs around £15 per roll, while reflector panels are more expensive – around £24 for three sheets or £30-35 for five sheets. Both are available both from local DIY stores and online. In addition to the foil or panels you’ll need a measuring tape, scissors (or a Stanley knife) and some double-sided tape.
Follow these simple steps to fit your reflective foil:
- Clean behind the radiator – make sure the wall is dry, dust-free and clean.
- Measure the gap between the two brackets behind the radiator.
- Cut the radiator foil to fit this gap.
- Attach a line of double-sided sticky tape to the back of the radiator foil along one of the horizontal edges.
- Slide the radiator foil down behind the radiator with the reflective surface facing away from the wall and then run your hand along the top of the foil to stick the tape to the wall.
Other smart ways to make radiators more efficient
You can improve the performance of your radiators in other ways too:
- Regularly bleed your radiator to release trapped air
- Avoid placing furniture like sofas in front of your radiators and tuck curtains behind.
- Fit a radiator shelf above the radiator to help force air out into the room
- Fit thermostatic radiator valves, allowing you to set different temperatures in individual rooms to reduce energy use
- Switch to smart heating controls (including smart thermostatic radiator valves) to maximise efficiency by fine-tuning energy settings over a 24-hour period.
Thermal curtains and lined blinds
What are thermal curtains and how do they work?
Thermal curtains reduce the transfer of heat through your windows by combining several layers of material to slow down the transfer – known as conduction – of heat from the room to the outside. They can be purchased wholly made or you can buy a thermal lining to attach to existing curtains.
The thermal lining is made up of a thick fabric backed with an insulating layer. Look for fabrics with a special metallic side designed to reflect heat back into the home in a similar way radiator foil does to further reduce heat loss.
Another option are thermal blinds, which work in both directions, trapping heat in your home during the winter months while reflecting sunlight from outside in summer to help keep the room cooler. If fitted to cover the entire window, both blinds and curtains can also reduce draughts from poorly sealed or single-glazed windows with large panes of glass, although they can’t completely seal them, so heat can still leak out.
Do thermal curtains and lined blinds actually work?
A recent study by the University of Salford estimates the simple act of drawing blinds or curtains during winter can reduce heat loss by 15-17%. Another study by Salford’s Energy Hub revealed that blinds and shutters can have a positive effect even on energy-efficient double-glazed windows, with heat loss reduced by up to 33% depending on the type of blind or shutter used. By cutting heat loss, the room requires less heat to maintain a comfortable temperature, helping reduce energy bills.
How to use thermal curtains and lined blinds effectively
To get the best results from your thermal curtains and blinds, make sure you consider the following when purchasing:
- Choose a multi-layered thermal curtain to maximise heat retention
- If budgets are tight, consider purchasing thermal linings that can be sown into existing curtains
- When choosing blinds, look for extra features – side-opening zip roller blinds for large windows or vertically slatted blinds that can be partially opened or closed as required.
It’s also important you choose the right size and placement for your curtains. When hanging the curtains, ensure they:
- are hung a few inches or centimetres above the window
- also overlap the window by a few centimetres on either side
- hang at least a few centimetres below the window (or ideally to the floor if practical)
- overlap in the middle so the window is fully covered. Also consider using Velcro or magnets to enhance the seal
- as close to the window as possible to minimise or eliminate gaps.
When fitting blinds, use inside-recess or clip-on blinds with the reflective side of the thermal linings facing the window.
To get the most from your curtains or blinds, make sure they’re open when needed – for example, during winter days when the sun is shining – and closed when you need to either trap heat inside (typically at dusk) or to keep the sun out during hot days.
Draught excluders for doors and windows
What are draught excluders and how do they work?
Draught excluders seal off gaps in windows and doors using a variety of materials depending on the gap being sealed. Their purpose is to improve insulation by preventing warm air from leaking out or cold air blowing in.
Draught excluders are commonly fitted to doors, but can also be fitted to windows, letter boxes, keyholes, unused vents and even chimneys.
Do draught excluders actually make a difference?
Yes, draught excluders do make a difference – and come officially recommended across a range of government publications, including this two-page factsheet highlighting suggested practices to follow. Numerous studies have shown how draught excluders help reduce heat loss from homes – including the University of Nottingham’s E.ON 2016 Research House, where simple draught-proofing measures reduced air permeability by 30%.
In terms of real-world savings, the Energy Saving Trust says that draughtproofing doors and windows can save £40-45 a year in energy bills, while draughtproofing your chimney could cut a further £60-65.
Draughtproofing measures are most effective in older and period properties but will make a difference in any dwelling with poorly fitted doors and windows with gaps. However, they can’t perform miracles and won’t last forever, so consider replacing doors and windows for a more effective solution.
How to use draught excluders effectively
Fitting draught excluders is often a job you can do yourself with a little preparation and care. First, make sure you have the proper tools required depending on what you wish to draught proof:
- Door: use a brush draught excluder to seal gaps at the bottom of the door, or draught-proofing strips to seal gaps around the rest of the frame. You can also purchase keyhole covers and letter box flaps or brushes – measure to fit
- Windows that open: use self-adhesive foam strips for a temporary fix, or metal/plastic strips with brushes or wipers for a longer-term solution. Choose the correct size for your window to avoid gaps or preventing the window from closing properly
- Sash windows: use brush strips or get professional help
- Window frames: use a silicone-based sealant to plug any gaps
- Chimney: a permanent solution is to fit a cap over the pot, but is expensive and requires expert installation. A chimney draft excluder works a bit like a balloon to fill the gap in the vent and can be fitted from below – it can also be removed to light fires if needed.
Avoid closing off ventilation where it exists for a specific reason – for example, trickle or air vents designed to avoid the buildup of moisture in places in like the bathroom or kitchen. Rooms with flues or open fires need adequately ventilation too.
Window insulation film
What is DIY window insulation film and how does it work?
Window insulation film is specialist transparent film designed to augment existing glazing. Like regular double-glazing it traps an insulating layer of air between the film and window pane to help keep conditions warmer in winter and cooler in summer.
It’s not as effective as upgrading your windows, but insulation film can improve performance and is particularly effective on single-glazed windows or windows with draughty panes. It’s potentially a good option for those living in listed or older building where new windows aren’t feasible.
Does DIY window insulation film actually work?
Most reference studies focus on insulation film’s cooling properties, with one UK hotel case study reporting it reduced cooling energy consumption by 35% in the summer. Similarly, the Energy Saving Trust recommends adding solar film as a cooling device.
However, there are many anecdotal reports of the film’s effectiveness during the damper, colder months. One Tiktok user has claimed fitting insulation film halved her electricity bill, while reviews of insulation kits from reputable manufacturers like Stormguard and Duck have found that fitting the film has made rooms more comfortable, reduced draughts through leaky panes and reduced the amount of condensation, particularly on single-paned windows.
On the downside, insulation film is quite obtrusive and can look a bit cheap. It can also be difficult to fit (see below) and will need to be replaced every winter.
How to apply window insulation film effectively
When it comes to fitting window insulation film, make things easier for yourself by preparing thoroughly. First, make sure you have everything you need:
- The film kit – prices vary from around £10-20 to fit one window to £50 to fit up to 10
- Double-sided tape – makes installation easier if it’s not provided in the kit
- Scissors
- Hair dryer (or heat gun)
Follow these steps to fit insulation film:
- Prepare the window – remove any dust and grime with a damp cloth and let surfaces dry.
- Measure and cut film – be sure to add on a few extra centimetres on each side to make it easier to handle and ensure the pane is completely covered.
- Apply tape – apply your double-sided tape along the edge of the frame and not on the glass to ensure it can form an air pocket.
- Attach film – start in one corner and ensure a tight fit by keeping the film taut as you press it along the double-sided tape.
- Shrink film – use a hairdryer or heat gun on a low setting across the film to shrink and smooth out.
- Trim excess – use sharp scissors or cutting knife to remove any excess film (leave a 2-mm gap along the edges).
- Be patient – any mottled or hazy appearance should vanish as the film cures over a 2-4 week period.
Avoid these mistakes for the best results:
- Avoid cheap kits – choose one from a reputable manufacturer like 3M, Duck and Stormguard
- Don’t apply on a windy or damp day
- Avoid heating any one area for too long with the hairdryer or heat gun to avoid burning
- Avoid cleaning for 4 weeks – and then only wipe with a soft chamois leather and clean water (no abrasive cleaning materials).
Pipe lagging
What is pipe lagging and how does it work?
Lagging pipes wraps them in an insulated material – typically a sleeve or wrap – that helps retain heat and reduce the risk of freezing in sub-zero temperatures. Lagging is usually applied to pipes in exposed areas, such as external walls as well as in garages, lofts, basements and under sinks.
Does pipe lagging actually make a difference?
Insulating pipes is a proven method for boosting thermal efficiency and is frequently cited in official publications, building regulations and UK standards (specifically BS 5422).
The primary benefits of pipe lagging are:
- Reduces heat loss
- Improves boiler efficiency
- Reduces risk of freezing and burst pipes.
It’s worth noting that lagging your pipes won’t make a huge difference to your energy bill on its own – make sure you insulate other parts of your home too, including your hot water cylinder and loft areas.
How to install pipe lagging effectively
Insulating your pipes is relatively straightforward, so long as you follow the right path:
- Measure your pipe diameters – also measure the length of the uninsulated pipe you need to lag.
- Purchase your insulation – you’ll find most DIY stores carry foam pipe insulation. Make sure the bore size matches the diameter of your pipes when purchasing. Most lagging comes in 1-metre lengths, and costs less than £5 per metre, but longer sizes are available.
- Assemble your tools –you’ll also need a sharp knife or scissors to cut the insulation to length. If you need to fit multiple 1m lengths, consider purchasing specialist insulation pipe wrap for joining two pieces together. Also look for insulated elbow joint covers for any 90-degree turns.
- Cut to size and fit – measure the length of your pipe and cut the foam sleeves to fit. Then push the sleeve(s) over the pipes, using the cut along its length to snap into place.
Mistakes to avoid:
- Choosing the wrong material – foam insulation is best for indoor pipes as it perishes quickly in sunlight or rain unless wrapped in UV-resistant, waterproof tape. Rubber is recommended for lagging outdoor pipes
- Using the wrong size – make sure the sleeve fits snugly around the pipe
- Leaving gaps – this increases the risk of those unprotected areas freezing, and is particularly true at joints or where the pipes meet tanks or cylinders – if necessary, wrap them in specialist lagging tape or use cable ties to secure sections
- Ignoring unseen pipes – if pipes go into invisible spaces like airing cupboards, lofts or under the floor, don’t forget to insulate these parts too
- Cover leaky pipes – repair the leak before lagging them to avoid damp (and less effective) lagging.
What doesn’t work (or isn’t worth the hype)
Not all insulation “hacks” are worth the time and effort. These offer little or no benefit:
- Kitchen foil as a radiator reflector
Kitchen foil is far less effective than dedicated radiator reflector foil – and will need replacing frequently as the foil dulls and oxidises.
- Cling film over windows
Cling film has no insulating air gap and peels off quickly.
- Bubble wrap on windows
This blocks light, looks unsightly and crucially can trap condensation on windows to potentially damage frames.
- Tea lights in flower pots (aka the terracotta heater)
This approach offers negligible heat benefits and is a fire hazard to boot.
- Taping bin bags to windows or walls
Offers no insulation, but does increase the risk of damp, condensation and mould.
- Rugs on walls
Rugs offer little or no thermal barrier and are another potential creator of damp..
- Closing off unused rooms without heating them
You risk damp, mould and potentially frozen pipes.
- Over-insulating with no ventilation
Reduces indoor air quality through trapping moisture, which leads to condensation and mould.
Tips for renters: how to keep your home warm without losing your deposit
If you rent your home, then applying these hacks may breach your tenancy agreement if you’re not careful. The key is to make your fixes temporary, so they can be removed without damaging the underlying fabric of your house.
Focus on smart use of soft furnishing – fit heavy or thermal curtains for your windows and place rugs on bare floors, for example. Use removable foam strips or draught snakes to block gaps in doors and windows. And be smart about closing internal doors to keep warmth in each room. Cold spots in rooms can be isolated from warmer areas by placing freestanding shelves or room dividers.
Other fixes covered above you can safely fit include:
- Window insulation film
- Chimney balloons
- Radiator reflector panels – choose cut-to-fit sheets that simply slot behind radiators without requiring fixing to the wall
- Easily removable foam insulation to lag pipes.
When applying anything – including temporary insulation – to your walls, use the following removable fittings:
- Removable adhesive hooks and strips or suction cup hooks – perfect for lightweight items like window insulation film or thermal curtains
- Magnetic strips – to attach items like radiator panels to metallic objects (the radiator)
- Pressure-fit rods – another option for fitting thermal curtains in bay windows or areas with small gaps
- Tension-fit draught stoppers – these spring-loaded door seals require no screws or nails.
